No. 1, August, 1920] GENETICS 47 



351. Db Winiwarter. H. Les mitoses de 1 epithelium seminal du chat. [Mitoses of 

 the seminal epithelium of the cat.] Arch. Biol. 30: 1 87. / doublt pi. withSAfig. 1919. — 

 Thirty-six chromosomes occur in odgonial cells, thirty-five in spermatogonia!, the difference 

 depending on the hcterochromosomes. The thirty-four autosomes unite to form seventeen 

 bivalents in the primary spermatocyte, the heterochromosome constituting an eighteenth 

 element. Secondary spermatocytes have eighteen and seventeen chromosomes respectively, 

 and these numbers are maintained in the spermatids and consequently in the spermatozoa, 

 since the last division is an equation-division. The heterochromosome is not detectable in 

 the spermatogonia but appears gradually in the telophase of the last spermatogonial division. 

 It finally becomes visible as an elongated body, often curved or even sharply bent. It never 

 appears double as does its homologue in the oocyte. It is readily distinguished from the nu- 

 cleolus, which is spherical and visible in spermatogonia as well as in the spermatocytes. — 

 Author believes that his earlier counts in oogenesis, in which he and Saintmont recorded 

 twelve chromosomes on the first maturation spindle and estimated twenty-four as the somatic 

 number, were incorrect. He now thinks that the division figures were abnormal or that in 

 fixation the chromosomes agglutinated. — Various authors have described a "monosome" in 

 the germ-cells of the female cat but author is convinced that what they have regarded as a 

 single body is the two heterochromosomes in juxtaposition. — The observational part of the 

 paper is followed by twenty-six pages of discussion of the literature and of general aspects 

 of the work. — M. F. Guyer. 



352. Doblas, Jose Herrera. Seleccion de semillas. [Seed selection.] Bol. Assoc. 

 Agric. Espafia 11 : 90-95. 1919. 



353. Dodge, Raynal. Aspidium cristatum X marginale and A. simulatum. Amer. 

 Fern Jour. 9: 73-SO. 1919.— Extracts from letter written to C. H. Knowlton by Dodge in 

 1907 containing a detailed account of his discovery of the Massachusetts fern and the hy- 

 brid between the crested and marginal ferns. — F. C. Anderson. 



354. Dresel, Kurt. Inweiferngelten dieMendelschenVererbungsgesetze in der mensch- 

 lichen Pathologie? [To what extent do Mendelian laws of heredity hold in human pathology?] 

 Virchow's Arch. 224: 256-303. 1917.— In general, the so-called laws of heredity (e.g., the "law 

 of filial regression") are not such in the strictest sense, but the Mendelian law does present a 

 conception which is fundamental to the study of human heredity. Hereditary disease may 

 be due to single dominant or recessive factors or to combinations of factors. Occasional de- 

 partures from expected results seeming to show incomplete dominance are due to the chance 

 absence from the germplasm of a second factor which is usually present in homozygous form 

 and which is essential to the actual manifestation of the condition. Sex-linked inheritance 

 is wholly in accord with Mendel's law arid is the expression of a certain degree of affinity be- 

 tween the sex factor ("gamete") and the disease-favoring factor. Since the proportion of 

 affected individuals and female carriers is believed frequently to be high in sex-linked inherit- 

 ance, the occasional presence of two equally potent but independent factors is suggested. 

 The essay, which received the "Schulze Preis," is illustrated by forty-seven graphic diagrams 

 and several tables classifying human diseases on the basis of their behavior in heredity. There 

 is a rather extensive bibilography. — C. H. Danforth. 



355. Dreyer, Th. F. A suggested mechanism for the inheritance of acquired characters. 

 South African Jour. Sci. 14: 272-277. 1918. 



356. Drude, O. Erfahrungen bei Kreuzungsversuchen mit Cucurbita Pepo. [Experi- 

 ences in crossing experiments with Cucurbita Pepo.] Ber. Deutsch. Bot. Ges. 35: 26-57. 

 1 pi. 1918. 



357. Dunn, L. C. The sable varieties of mice. Amer. Nat, 54: 247-261. S fig. May- 

 June, 1920. — Sable is a form of yellow mouse showing considerable dark pigment on dorsal 

 and lateral aspects. Black and tan is an extreme type of this variety. Darkness of sables 



